ps. as an aside: We should be careful not to suggest that debate performance doesn’t influence the media narrative. It does. But as John’s post notes, the effect of debates filtered by the media will differ from what the effect would have been if it had not been filtered.Yup. I mean, to take the extreme case: it's hard to believe that anyone could have watched the "oops" debate and not come away with any headline other than that Rick Perry goofed in a big way. Except...well, even that one isn't true, if we think about it. I mean, you could basically ignore Perry, and focus on the other candidates, and that would push "oops" to the side, right? Or you could, I suppose, do a substance-heavy analysis that ignored as much as possible the stagecraft and theater aspects. Or...well, I looked back at my own reactions, and while I immediately acknowledged the magnitude of "oops," my main focus at my Plum Line wrap was on Herman Cain, and then went into lots of detail on Cain's performance the next day. Which isn't to say that I was "right" or anything, just that a lot of what people (myself certainly included) see in this stuff is extremely subjective, and it's very difficult to sort out how much of the eventual version that people are exposed to once it's through the filter is the debate itself and how much is the filter.
Now, the study I referred to earlier cuts through that by just measuring people's reactions based on whether they were exposed to the filtered or unfiltered debate (or both). And that's a good approach to the question they were asking. But if your interest is in how and why debates are filtered as they are, well, that's a pretty tricky problem, it seems to me.